Check file type (FLV) before PHP upload file in temporary folder by reading only starting 3 bytes of file

Question

First 3 bytes of FLV file are signature \"FLV\". Now my question:

Is there any possibility in PHP to handle file uploads so that we can hook into the input stream of

Answer 1

First, set session.upload_progress.enabled in your php.ini.

Then, use session.upload_progress to track how many bytes have uploaded. Once you have reached the minimum threshold, check the temporary file being uploaded, it will be in $_SESSION[unique_key]['files'][0]['tmp_name']. If the file doesn't match, set $_SESSION[unique_key]["cancel_upload"] to TRUE, and the file will be rejected.

To get unique_key:

ini_get("session.upload_progress.prefix") . $_POST[ini_get("session.upload_progress.name")];

If the above does not work (I haven't tested it), then your only recourse would be to create your own custom handler for PHP either as an Apache module (or better, as a custom CGI application). There you could do your filtering.

Answer 2

@burhan-khalid provided a more up to date and correct answer above.

Short Answer is no with your constraints.

You can not access that file with PHP until it has been uploaded to the server. After it is uploaded you can read it but not before, at least not without some type of client side software that would allow you to stream it to PHP instead of the normal form submission.